Display device with improved luminance

Patent metadata

Field	Value
Publication number	US-9852701-B2
Application number	US-201615083429-A
Country	US
Kind code	B2
Filing date	Mar 29, 2016
Priority date	Apr 21, 2011
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A display device is provided. The display device includes a display unit having pixels arranged in a two-dimensional matrix, each pixel including additive mixture subpixels and a luminance adjustment subpixel, and a signal control unit controlling a luminance at a maximum gray scale in the luminance adjustment subpixel depending on an external light illuminance.

First claim

What is claimed is:

1. A display device comprising:
a display unit having pixels arranged in a two-dimensional matrix, each pixel including additive mixture subpixels and a luminance adjustment subpixel; and
a signal control unit configured to control a luminance at a maximum gray scale in the luminance adjustment subpixel, the signal control unit including:
a photo sensor configured to produce a photo output based on an external light illuminance, and
a signal control circuit comprising:
a first converting circuit configured to generate video signals for driving the additive mixture subpixels, the video signals being set corresponding to gray scales of input signals; and
a second converting circuit configured to generate an adjustment pixel video signal for driving the luminance adjustment subpixel, the adjustment pixel video signal being generated according to the photo output from the photo sensor,

wherein only the luminance at the maximum gray scale in the luminance adjustment subpixel is controlled depending on the external light illuminance, and
wherein the signal control unit is configured to control the luminance in the luminance adjustment subpixel independently of the additive mixture subpixels.

2. The display device according to claim 1 , wherein the display unit is a reflective or transflective display unit.

3. The display device according to claim 1 , wherein the luminance at the maximum gray scale in the luminance adjustment subpixel is controlled to decrease as the external light illuminance increases.

4. The display device according to claim 1 , wherein the gray scale of the luminance adjustment subpixel is controlled using a signal indicating luminance information of the additive mixture subpixels.

5. The display device according to claim 4 , wherein the signal indicating the luminance information indicates a Y stimulus value.

6. The display device according to claim 1 , wherein the luminance adjustment subpixel displays a color having a saturation lower than saturations of colors displayed by the additive mixture subpixels.

7. The display device according to claim 6 , wherein the luminance adjustment subpixel displays white.

8. The display device according to claim 1 , wherein the luminance adjustment subpixel displays a color different from colors displayed by the additive mixture subpixels.

9. The display device according to claim 8 , wherein the luminance adjustment subpixel displays yellow or cyan.

10. The display device according to claim 9 , wherein
the additive mixture subpixels include a first subpixel, a second subpixel, and a third subpixel, and
the third subpixel that displays blue has a size larger than each of the first subpixel and the second subpixel.

11. The display device according to claim 1 , wherein a voltage applied to a pixel electrode of the luminance adjustment subpixel at the maximum gray scale increases as the external light illuminance increases.

12. The display device according to claim 1 , wherein predetermined reference voltages include:
a high scale voltage that is a reference voltage applied to the first converting circuit at the maximum gray scale, and
a low scale voltage that is a reference voltage applied to the first converting circuit at the minimum gray scale, and
wherein the video signals are set corresponding to gray scales of input signals and based on the predetermined reference voltages.

13. The display device according to claim 12 , wherein the first converting circuit is to configured to:
output the video signals to have values closer to the high scale voltage as the gray scale values of the input signals become closer to the maximum gray scale, and
output the video signals to have values closer to the low scale voltage as the gray scale values of the input signals become closer to zero.

14. The display device according to claim 12 , wherein the signal control circuit is configured to:
set an external-light reference voltage to the high scale voltage when a value of the photo output is equal to or less than a first level,
set an external-light reference voltage between the high scale voltage and the low scale voltage when the value of the photo output is between the first level and a second level higher than the first level, and
set an external-light reference voltage to the low scale voltage when the value of the photo output is equal to or greater than the second level,
wherein the adjustment pixel video signal is generated according to the external light reference voltage.

Assignees

• Japan Display Inc

Inventors

• Kurasawa Hayato
• Watanabe Yoshihiro

Classifications

• G09G2320/0666

  for control of colour parameters, e.g. colour temperature · CPC title

• G09G3/2003

  Display of colours (specific for liquid crystal displays G09G3/3607) · CPC title

• G09G3/3648 Primary

  using an active matrix (G09G3/367 - G09G3/3696 take precedence) · CPC title

• G09G3/3413

  Details of control of colour illumination sources · CPC title

• G09G3/3677

  suitable for active matrices only · CPC title